> If you find that your documents are not being served as you prescribe by
> your Markup -- for instance as text/html when you specified
> application/xhtml+xml - - contact your Web Host/Service Provider
> ..........

That should read:

.......... If you find that your documents are not being served as you
prescribe by your Markup -- in multiple browsers -- for instance as
text/html when you specified application/xhtml+xml - - contact your Web
Host/Service Provider ............